Merge branch 'master' into RegularExpressionMatching

Author: jayeshrdeotalu

.github/workflows/build.yml

@@ -10,7 +10,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           java-version: 21
-          distribution: 'adopt'
+          distribution: 'temurin'
       - name: Build with Maven
         run: mvn --batch-mode --update-snapshots verify
       - name: Upload coverage to codecov (tokenless)

.github/workflows/codeql.yml

@@ -30,7 +30,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           java-version: 21
-          distribution: 'adopt'
+          distribution: 'temurin'
 
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v3

.github/workflows/infer.yml

@@ -18,7 +18,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           java-version: 21
-          distribution: 'adopt'
+          distribution: 'temurin'
 
       - name: Set up OCaml
         uses: ocaml/setup-ocaml@v3

DIRECTORY.md

@@ -0,0 +1,28 @@
+package com.thealgorithms.bitmanipulation;
+
+/**
+ * @author - https://github.com/Monk-AbhinayVerma
+ * @Wikipedia - https://en.wikipedia.org/wiki/Ones%27_complement
+ *            The class OnesComplement computes the complement of binary number
+ *            and returns
+ *            the complemented binary string.
+ * @return the complimented binary string
+ */
+public final class OnesComplement {
+    private OnesComplement() {
+    }
+
+    // Function to get the 1's complement of a binary number
+    public static String onesComplement(String binary) {
+        StringBuilder complement = new StringBuilder();
+        // Invert each bit to get the 1's complement
+        for (int i = 0; i < binary.length(); i++) {
+            if (binary.charAt(i) == '0') {
+                complement.append('1');
+            } else {
+                complement.append('0');
+            }
+        }
+        return complement.toString();
+    }
+}

src/main/java/com/thealgorithms/bitmanipulation/OnesComplement.java

@@ -0,0 +1,39 @@
+package com.thealgorithms.bitmanipulation;
+
+/**
+ * Utility class to find the single non-duplicate element from an array
+ * where all other elements appear twice.
+ * <p>
+ * The algorithm runs in O(n) time complexity and O(1) space complexity
+ * using bitwise XOR.
+ * </p>
+ *
+ * @author <a href="http://github.com/tuhinm2002">Tuhin M</a>
+ */
+public final class SingleElement {
+
+    /**
+     * Private constructor to prevent instantiation of this utility class.
+     * Throws an UnsupportedOperationException if attempted.
+     */
+    private SingleElement() {
+        throw new UnsupportedOperationException("Utility Class");
+    }
+
+    /**
+     * Finds the single non-duplicate element in an array where every other
+     * element appears exactly twice. Uses bitwise XOR to achieve O(n) time
+     * complexity and O(1) space complexity.
+     *
+     * @param arr the input array containing integers where every element
+     *            except one appears exactly twice
+     * @return the single non-duplicate element
+     */
+    public static int findSingleElement(int[] arr) {
+        int ele = 0;
+        for (int i = 0; i < arr.length; i++) {
+            ele ^= arr[i];
+        }
+        return ele;
+    }
+}

src/main/java/com/thealgorithms/bitmanipulation/SingleElement.java

@@ -0,0 +1,26 @@
+package com.thealgorithms.bitmanipulation;
+
+/**
+ * Swap every pair of adjacent bits of a given number.
+ * @author Lakshyajeet Singh Goyal (https://github.com/DarkMatter-999)
+ */
+
+public final class SwapAdjacentBits {
+    private SwapAdjacentBits() {
+    }
+
+    public static int swapAdjacentBits(int num) {
+        // mask the even bits (0xAAAAAAAA => 10101010...)
+        int evenBits = num & 0xAAAAAAAA;
+
+        // mask the odd bits (0x55555555 => 01010101...)
+        int oddBits = num & 0x55555555;
+
+        // right shift even bits and left shift odd bits
+        evenBits >>= 1;
+        oddBits <<= 1;
+
+        // combine shifted bits
+        return evenBits | oddBits;
+    }
+}

src/main/java/com/thealgorithms/bitmanipulation/SwapAdjacentBits.java

@@ -0,0 +1,41 @@
+package com.thealgorithms.bitmanipulation;
+
+/**
+ * @wikipedia - https://en.wikipedia.org/wiki/Two%27s_complement
+ *            This Algorithm was first suggested by Jon Von Neumann
+ * @author - https://github.com/Monk-AbhinayVerma
+ * @return the two's complement of any binary number
+ */
+public final class TwosComplement {
+    private TwosComplement() {
+    }
+
+    // Function to get the 2's complement of a binary number
+    public static String twosComplement(String binary) {
+        StringBuilder onesComplement = new StringBuilder();
+        // Step 1: Find the 1's complement (invert the bits)
+        for (int i = 0; i < binary.length(); i++) {
+            if (binary.charAt(i) == '0') {
+                onesComplement.append('1');
+            } else {
+                onesComplement.append('0');
+            }
+        }
+        // Step 2: Add 1 to the 1's complement
+        StringBuilder twosComplement = new StringBuilder(onesComplement);
+        boolean carry = true;
+        for (int i = onesComplement.length() - 1; i >= 0; i--) {
+            if (onesComplement.charAt(i) == '1' && carry) {
+                twosComplement.setCharAt(i, '0');
+            } else if (onesComplement.charAt(i) == '0' && carry) {
+                twosComplement.setCharAt(i, '1');
+                carry = false;
+            }
+        }
+        // If there is still a carry, append '1' at the beginning
+        if (carry) {
+            twosComplement.insert(0, '1');
+        }
+        return twosComplement.toString();
+    }
+}

src/main/java/com/thealgorithms/bitmanipulation/TwosComplement.java

@@ -0,0 +1,71 @@
+package com.thealgorithms.ciphers;
+
+/**
+ * The Atbash cipher is a simple substitution cipher that replaces each letter
+ * in the alphabet with its reverse.
+ * For example, 'A' becomes 'Z', 'B' becomes 'Y', and so on. It works
+ * identically for both uppercase and lowercase letters.
+ * It's a symmetric cipher, meaning applying it twice returns the original text.
+ * Hence, the encrypting and the decrypting functions are identical
+ * @author https://github.com/Krounosity
+ * Learn more: https://en.wikipedia.org/wiki/Atbash
+ */
+
+public class AtbashCipher {
+
+    private String toConvert;
+
+    // Default constructor.
+    AtbashCipher() {
+    }
+
+    // String setting constructor.
+    AtbashCipher(String str) {
+        toConvert = str;
+    }
+
+    // String getter method.
+    public String getString() {
+        return toConvert;
+    }
+
+    // String setter method.
+    public void setString(String str) {
+        toConvert = str;
+    }
+
+    // Checking whether the current character is capital.
+    private boolean isCapital(char ch) {
+        return ch >= 'A' && ch <= 'Z';
+    }
+
+    // Checking whether the current character is smallcased.
+    private boolean isSmall(char ch) {
+        return ch >= 'a' && ch <= 'z';
+    }
+
+    // Converting text to atbash cipher code or vice versa.
+    public String convert() {
+
+        // Using StringBuilder to store new string.
+        StringBuilder convertedString = new StringBuilder();
+
+        // Iterating for each character.
+        for (char ch : toConvert.toCharArray()) {
+
+            // If the character is smallcased.
+            if (isSmall(ch)) {
+                convertedString.append((char) ('z' - (ch - 'a')));
+            }
+            // If the character is capital cased.
+            else if (isCapital(ch)) {
+                convertedString.append((char) ('Z' - (ch - 'A')));
+            }
+            // Non-alphabetical character.
+            else {
+                convertedString.append(ch);
+            }
+        }
+        return convertedString.toString();
+    }
+}

src/main/java/com/thealgorithms/ciphers/AtbashCipher.java

@@ -27,13 +27,13 @@ private ColumnarTranspositionCipher() {
      * @return a String with the word encrypted by the Columnar Transposition
      * Cipher Rule
      */
-    public static String encrpyter(String word, String keyword) {
+    public static String encrypt(final String word, final String keyword) {
         ColumnarTranspositionCipher.keyword = keyword;
-        abecedariumBuilder(500);
+        abecedariumBuilder();
         table = tableBuilder(word);
         Object[][] sortedTable = sortTable(table);
         StringBuilder wordEncrypted = new StringBuilder();
-        for (int i = 0; i < sortedTable[i].length; i++) {
+        for (int i = 0; i < sortedTable[0].length; i++) {
             for (int j = 1; j < sortedTable.length; j++) {
                 wordEncrypted.append(sortedTable[j][i]);
             }
@@ -51,11 +51,12 @@ public static String encrpyter(String word, String keyword) {
      * @return a String with the word encrypted by the Columnar Transposition
      * Cipher Rule
      */
-    public static String encrpyter(String word, String keyword, String abecedarium) {
+    public static String encrypt(String word, String keyword, String abecedarium) {
         ColumnarTranspositionCipher.keyword = keyword;
         ColumnarTranspositionCipher.abecedarium = Objects.requireNonNullElse(abecedarium, ABECEDARIUM);
         table = tableBuilder(word);
         Object[][] sortedTable = sortTable(table);
+
         StringBuilder wordEncrypted = new StringBuilder();
         for (int i = 0; i < sortedTable[0].length; i++) {
             for (int j = 1; j < sortedTable.length; j++) {
@@ -72,7 +73,7 @@ public static String encrpyter(String word, String keyword, String abecedarium)
      * @return a String decrypted with the word encrypted by the Columnar
      * Transposition Cipher Rule
      */
-    public static String decrypter() {
+    public static String decrypt() {
         StringBuilder wordDecrypted = new StringBuilder();
         for (int i = 1; i < table.length; i++) {
             for (Object item : table[i]) {
@@ -91,14 +92,14 @@ public static String decrypter() {
      */
     private static Object[][] tableBuilder(String word) {
         Object[][] table = new Object[numberOfRows(word) + 1][keyword.length()];
-        char[] wordInChards = word.toCharArray();
-        // Fils in the respective numbers
+        char[] wordInChars = word.toCharArray();
+        // Fills in the respective numbers for the column
         table[0] = findElements();
         int charElement = 0;
         for (int i = 1; i < table.length; i++) {
             for (int j = 0; j < table[i].length; j++) {
-                if (charElement < wordInChards.length) {
-                    table[i][j] = wordInChards[charElement];
+                if (charElement < wordInChars.length) {
+                    table[i][j] = wordInChars[charElement];
                     charElement++;
                 } else {
                     table[i][j] = ENCRYPTION_FIELD_CHAR;
@@ -116,7 +117,7 @@ private static Object[][] tableBuilder(String word) {
      * order to respect the Columnar Transposition Cipher Rule.
      */
     private static int numberOfRows(String word) {
-        if (word.length() / keyword.length() > word.length() / keyword.length()) {
+        if (word.length() % keyword.length() != 0) {
             return (word.length() / keyword.length()) + 1;
         } else {
             return word.length() / keyword.length();
@@ -173,13 +174,11 @@ private static void switchColumns(Object[][] table, int firstColumnIndex, int se
     }
 
     /**
-     * Creates an abecedarium with a specified ascii inded
-     *
-     * @param value Number of characters being used based on the ASCII Table
+     * Creates an abecedarium with all available ascii values.
      */
-    private static void abecedariumBuilder(int value) {
+    private static void abecedariumBuilder() {
         StringBuilder t = new StringBuilder();
-        for (int i = 0; i < value; i++) {
+        for (int i = 0; i < 256; i++) {
             t.append((char) i);
         }
         abecedarium = t.toString();